Hydraulic mechanism for actuating valves



Oct. 28, 1952 P. T. TUCKER 2,615,438

HYDRAULIC MECHANISM FOR ACTUATING VALVES Filed Aug. 4. 1948 Patented Oct. 28, 1952 HYDRAULIC MECHANISM FOR ACTUATING VALVES Preston T. Tucker, Ypsilanti, Mich. Application August 4, 1948, Serial No. 42,477

.ent invention to provide an improved hydraulic mechanism for operating valves which is not sensitive to temperature changes associated with engine operation.

Further, it is an object of the present inven-,

tion to provide an improved hydraulic mechanism for cyclically actuating a valve in accord with the movements of a cam.

Another object of the present invention'is to provide an improved hydraulic mechanism for operating valves which is particularly suitable for use on automobileengines.

Yet another object'of the present invention is to provide an improved hydraulic mechanism for operating the valves of an internal combustion engine which embodies features of construction, combination, and arrangement rendering it simple in construction and reliable in operation to the end that a maximum degree of utility is achieved.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention, itself, however, both asto its organization and method of operation together with further objects and advantages thereof, may best be understood by reference tothe following description taken in connection with the accompanying drawing in which: I

Figure 1 is a cross sectional view of one embodiment of the mechanism of the present invention showing fragmentary portions of an engine operably associated therewith; and

Figure 2 is a cross sectional view showing an alternative construction of the structure of Figure 1.

In Figure 1, a pistonlll of an internal combus-- tion engine is shown in its associated cylinder l2, the cylinder being shown incrosssection to display clearly the pistonand associa ed mechanism.

5 Claims. (Cl. 12390) The connecting rod I 4 is pivotally attached'at its opposite ends to the piston lo and crankshaft l6 to cause the latter to rotate in accord with the reciprocations of the piston. I

The head 22 of poppet valve I8 is, received in a beveled seat 20 fo rmed in the upper wall of the cylinder l2. This valve includes a stem portion 24 terminating in a cap portion 26. The spring vbottoms against the top wall of cylinder l2 and the portion 26 of valve 18 to urge the head 22 to a, closed position against seat 20.

The purpose of valve I8 is to admit fuel to cylinder I2 at predetermined points in the piston operating cycle. To that end, a chamber 29 is formed about valve seat 20 and is connected to source of operating fluid, such as a carburetor, (not shown) so that the cylinder I2 'is supplied with fuel when valve l8 opens.

The valve I8 is cyclically opened in accord with the movements of piston ID by the bellows 30. This bellows includes a lower end member 32 which bottoms against the end of the valve stem 24 and an upper end member 34 which is attached to the cam follower 36.

A pipe 38 is in fluid communication. with bellows 30 and extends outside of housing. '28 to the mounting plate 4!]. The bellows 42 is fixedly supported at one end from the mounting plate 40 by .bracket 54 and is in fluid communication with the interior of pipe 38. The other end of bellows 42 bottoms against cam follower 44 which rides against cam 46.

The cam 46 is driven by gears and 41 in accord with the rotations of the crank shaft IS.

The cam followers 36 and 44 are held for axial shifting movements by sleeve bearings 48 and 50 respectively. The former bearing is sustained by a bracket on the housing 28 and the latter by the bracket 54 which is held by mounting plate '40.

Hose connections 35 and 3? provide flexible connections between bellows'iifl and 42, respectively, and pipe 38.

The position of cam follower 36 is fixed by'the cam 56 against which it rides. This cam is pivotally attached to panel 53 by pin 58 and to arm 60 by link 62. The panel 53forms part of the housing 28 and extends in direction substantially parallel to cam 56. The arm 60 is held in position for axial shifting movements by the sleeve bearing 64 and is attached to one end of the bellows 66. The oppositepend of bellows 6B is at tached to the wall of housing 28.

The pipe 38 and the bellows 30 and 42 are filled with a suitable hydraulic control fluid, such as a mixture of alcohol and castor oil. As the cam 46 periodically shifts the cam follower 44, this fluid is driven from bellows 42 into bellows 30, thereby depressing the lower end 32 of bellows and opening valve I8. This cyclical valve operation is in timed sequence with the movements of piston II) and thereby admits fuel to the cylinder l2 at the proper times for good engine operation.

As the engine operates, the temperature of bellows 38 and 42, as well as pipe 38, increases. This increases the size of the cavity defined by these members and, in addition, increases the volume occupied by the hydraulic liquid. Since the linear coefilcient of expansion of the material of bellows 30 and 42 and pipe 38 does not ordinarily correspond with the volumetric rate of expansion of the fluid, the bellows 38 must expand or contract to make up the difference, thereby opening or closing valve I8 in the absence of movements of cam follower 44. In practical engine construction, the fluid expands at a greater volumetric rate than the rate corresponding to the linear expansion of the bellows 38 and 4,2 and pipe 38 and thus causes valve l8 to tend to open as the engine warms up.

In the apparatus of Figure 1, the valve actuating tendencies associated with engine heating are compensated or off-set by rotation of cam 56 which is rotated by bellows 66 and crank arm 60 asthe engine temperature rises. Since the bellows 30 rides against cam follower 36, counterclockwise rotation of the cam 56 bodily moves valve l8 to a more nearly closed position and thereby off-sets the tendency of increased fluid volume to open that valve.

The bellows 66 is mounted on housing 28 and thus participates in the engine heating. Since the bellows 30 and 42, as well as pipe 38, are subject to heating from the engine, they also participate in this heating. Consequently, bellows 66 partakes of temperature determined by the temperature of the fluid in the valve actuating mechanism.

Bellows 66 expands with temperature since a constant quantity of fluid is entrained therein, and the pressure in the chamber defined by housing 28 does not vary sufficiently to prevent such expansion. Thus, cam 58 is rotated in the counter-clockwise direction with increased engine temperature. The curvature of this cam is so proportioned that the resulting shifting movement of cam follower 38 varies the volume of bellows 38 by an amount just suflicient to off-set the difference in volume change of the hydraulic fluid and the volume change in the bellows 30 and c2 and pipe 38 associated with linear expansion.

In the modified form of the present invention shown in Figure 2, the bellows 42 has an extended portion 42a extending above the mounting plate 40. Passage 43 provides fluid communication between the two portions of bellows 42 so defined. The portion 42a is held against expansion under fluid pressure by the cam follower 360:. which rides on cam 56a and which is held for shifting movements by the sleeve bearing 64a. The cam 56a, is pivotally supported from panel 52a by the pin 58c, panel 52a being substantially parallel to cam 56a and forming part of housing 4!.

Hose 31a flexibly connects pipe 38 and bellows 42a.

The extended portion of bellows 42a is connected to pipe 38 which is in fluid communication with bellows 30a which operates to actuate valve 18a in the same manner as in the structure of Figure 1. However, the bellows 30a is supported by bracket 31 which is attached to the wall of housing 28.

The position of cam 55a, is controlled by bellows 6611 which engages crank arm 60a to shift that arm and rotate the cam. The crank arm 68a is held for shifting movements by the sleeve bearing 84a.

Since the bellows 66a is mounted on the wall of cylinder l2, it partakes directly of the engine temperature and, hence, varies in temperature in accord with the temperature of the fluid in bellows 38a, pipe 38, and bellows 42 and 42a. As the engine temperature increases, the cam 56a is rotated to allow bellows 42a to expand, thereby offsetting the tendency of the corresponding increase in fluid volume in bellows 38a, pipe 38,

I fluid, this operation being achieved by cam 58,

Figure 1.

It will, of course, be apparent to those skilled in the art that the bellows 38, 42, 30a, and 42a may be replaced by piston-cylinder combinations or other mechanisms defining cavities of variable volume and having spaced points movable relative to each other in accord with that volume. Moreover, it will be apparent that the bellows 66 and 66a may be replaced by other temperature responsive elements such as, for example, bimetallic elements. I

While I have shown two particular embodiments of my invention, it will, of course, be understood that I do not wish to be limited thereto since many modifications both in the parts themselves and in their cooperative structure may be made without departing from the spirit and scope I of my invention. I, of course, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What is claimed is:

1. A mechanism for actuating a valve in accord with the rotations of a cam, said mechanism comprising means defining a first fluid chamber of variable size and including a cam follower positioned for operative engagement with said-cam and operable to control the size of said first chamber, elements defining a second fluid chamber of variable size and in fluid communication with said first chamber and operable to move said valve in accord with the size of said second chamber, a fluid in said chambers having volume variable in accord with temperature to actuate said valve in accord with rotations of said cam, a movable member to limit movement of one of said chambers, and temperature responsive means operable to move said member thereby to vary the effective size of the chambers.

2. A mechanism for actuating a valve in accord with the rotations of acam, comprising a first device defining a cavity of size determined by the distance between two spaced points and attached to said valve at one of said points, a second devicedefining a cavity in fluid communication with saidfirst cavity and of size determined by. the

distance between two spaced points, a cam follower operably associated with said cam and in engagement with said last device at one of said points, a fluid in said cavities having a variation in volume with temperature, and means limiting movement of the other points on each of said devices, one of said means including temperature responsive elements disposed to partake of the temperature of said fluid and operable to shift the position of the corresponding other point to compensate for the temperature changes of said fluid.

3. A mechanism for actuating a valve in accord with the rotations of a cam, comprising a first bellows fixedly supported at one end, a cam follower in operative engagement with said cam and in engagement with said bellows, a second bellows having one end in engagement with said valve, means defining a fluid passage between said bellows, a fluid in said bellows having a' change in volume with temperature, and temperature responsive elements shiftably engaging the other end of said second bellows to limit movement thereof, said last named elements being positioned to partake of the temperature of said fluid and operable to compensate for the volume changes thereof With temperature.

4. A mechanism for actuating a valve in accord with the rotations of a cam, comprising a first bellows fixedly supported at one end, a cam follower in operative engagement with said cam and in engagement with said bellows, a second bellows in fluid communication with said first bellows and fixedly supported at one end, the other end of said second bellows being in engagement with said valve, a fluid in said bellows having a change in volume with temperature, a third bellows fixedly supported at one end and in communication with said first and second bellows, movable means to limit movement of the other end of the third bellows, and means operative to shift the movable means in accord with the temperature of said fluid to compensate for expansion thereof.

5. Mechanism for actuating a valve comprising a pair of expansible chambers each including two relatively movable parts, a conduit connecting the chambers in a closed fluid system, and means to limit movement of one of the parts of each chamber, the means to limit movement of at least one of the chambers being movable and including temperature responsive elements to move it.

PRESTON T. TUCKER.

REFERENCES CITED UNITED STATES PATENTS Name Date Nacker May '7, 1918 Number 

